According to German media, several artworks and ancient artifacts across four galleries on Berlin’s museum island were vandalized on October 3. An oily substance had been smeared on 63 pieces, including Egyptian sarcophagi, stone sculptures, and paintings at the Pergamon Museum, the Museum for Islamic Art, the Alte Nationalgalerie, and the Neues Museum, The Guardian reports.

The act of vandalism has been linked to recent conspiracy theories. One theory claims that the Pergamon Museum is the center of global satanism because it contains a reconstruction of the ancient Greek Pergamon Altar.

The damage is believed to have been caused by a water pistol or a syringe containing an oily fluid.

German celebrity Attila Hildmann, one of Germany’s most famous promoters of the unfounded QAnon conspiracy theory, recently posted messages on social media suggesting that German chancellor Angela Merkel was using the altar for “human sacrifices.”

The BBC reports that in August, when the Pergamon Museum was closed due to the COVID-19 pandemic, Hildmann described the ancient Greek Pergamon Altar as the “centre of global satanists and Corona criminals”.

Police in Berlin are now appealing to witnesses who may be able to identify the attacker.

Back in June, when the Pergomon was closed, conspiracy theorists spoke to supporters from the steps of the Altes Museum, describing the altar as satanic and the museum as a haven for “Corona criminals” and Satanists.